A common complaint about 802.11 wireless networking is that you can only connect to one wireless network at a time. For instance, if you are in an area where you have ad hoc (machine-to-machine) and infrastructure (wireless router) networks available, you cannot connect to both networks simultaneously.
As a way around this limitation, Microsoft Research has developed a software product called VirtualWiFi, which allows a single wireless LAN card to be "abstracted." This means that, to the user, it can appear as multiple network adapters, each with different connection properties. This would make it possible to connect to both ad hoc nodes and one or more infrastructure nodes simultaneously, although the total bandwidth available to the adapter would be divided across all the available connections.
Once installed, the software creates a "VirtualWiFi Virtual Miniport" adapter connection in the Network Connections window. To add more networks, you'll need to configure the virtual adapter from the command line (there is no GUI for the driver yet) as defined in the instructions for the driver.
Several caveats apply. Installing VirtualWiFi requires you to stop the Wireless Zero Configuration Service and any other third-party wireless networking adapter utilities. This means that 802.1x connections (i.e., 802.11g) or WEP or other wireless-encryption protocols will not work. Also, VirtualWiFi works if there is only one wireless adapter physically present. Other adapters cannot simply be disabled; they must be removed entirely. Although there is core-level support for more than one adapter, it hasn't been implemented as of this release.
According to Microsoft, this technique also allows you to make a home network "elastic" by adding access to nodes, which would normally be out of range to the central access point, and allowing access through ad hoc connections.
Serdar Yegulalp is editor of the Windows Power Users Newsletter. Check it out for the latest advice and musings on the world of Windows network administrators -- and please share your thoughts as well!